Tool for gear finish forming

ABSTRACT

A toothed tool for finish forming, by rolling, a cylindrical or helical work gear, said tool having, in the flanks of its teeth, serrations extending perpendicular to the axis of the tool which define flutes in the tooth flanks and intervening lands, the flutes on each tooth flank extending alternately from the tip towards the root and from the root towards the tip and extending along part only of the length of the tooth flank and being so disposed that corresponding flutes on successive tooth flanks are disposed helically on the circumference of the tool.

United States Patent 1 [111 3,777,345

Brown 1 Dec. 11, 1973 [54] TOOL FOR GEAR FI FORMING 3,704,612 12/1972Loos 72/102 Inventor: Graham Maurice Brown, Daventry, 3,733,886 5/1973Loos 29/1592 England I I Primary Examiner-Lowell A. Larson I73]Assrgnce: Machine Tool Divisional Services Atto y john w M n et Limited,Coventry, England [22] Filed: Sept. 18, 1972 21 A l N 289 831 [57]ABSTRACT l 1 PP i A toothed tool for finish forming, by rolling, acylindrical or helical work gear, said tool having, in the [30] ForeignApphcauon Priority Data flanks of its teeth, serrations extendingperpendicular Sept. 17, 1971 Great Britain ..43472/71 to the axis of thetool which define flutes in the tooth flanks and intervening lands, theflutes on each tooth [52] (1.8. CI. 72/102, 29/1592 flank extendingalternately from the tip towards the [51] Int. Cl B2lh 5/00 root andfrom the root towards the tip and extending [58] Field of Search 72/102;29/1592 along part only of the length of the tooth flank and being sodisposed that corresponding flutes on succes- [56] References Cited sivetooth flanks are disposed helically on the circum- UNITED STATES PATENTSference of the l,847,848 3/1932 Ragan 2 Claims 5 Drawing Figures3,631,703 1/1972 Bregi et al. 29/l 59.2

TOOL FOR GEAR FINISH FORMING It is known to finish form a cylindrical orhelical work gear by gear rolling. This procedure involves running thework gear in mesh with and with its axis parallel to that of acorrespondingly toothed driven tool, which forms the flanks of the teethof the work gear to the desired final configuration by effecting plasticdeformation of the metal of the work gear as distinct from removal ofmetal from the work gear by a cutting action as in gear shaving. Theradial thrust between the tool and the work gear is accordingly high andit has been proposed, with a view to reducing the reaction load whichhas to be taken, to form in the flanks of the teeth of the tool fluteswhich extend from tip to root of the teeth and which define between themlands which form the working faces of the tooth flanks.

The present invention provides a toothed tool for finish forming, byrolling, a cylindrical or helical work gear said tool having, in theflanks of its teeth, serrations extending perpendicular to the axis ofthe tool which'define flutes in the tooth flanks and intervening lands,the flutes on each tooth flank extending alternately from the tiptowards the root and from the root towards the tip and extending alongpart only of the length of the tooth flank and being so disposed thatcorresponding flutes on successive tooth flanks are disposed helicallyon the circumference of the tool.

The invention will now be further described with reference to theaccompanying diagrammatic drawings, in which,

FIG. 1 is a plan view of a gear rolling machine,

FIG. 2 is a diagram illustrating a helical gear in mesh with a formingtool,

FIG. 3 is an edge view showing part of a tool for forming a spur gear,

FIG. 4 is a section on the line IV IV in FIG. 3, and FIG. 5 is a sectionon the line V V in FIG. 4.

The machine shown in FIG. 1 is generally similar to the gear showingmachine described in British specification No. 987,972, being modifiedto provide an upfeed for the work gear appropriate for gear rolling andto dispense with traverse of the work gear. The work 7 the tooth flanks.

a of the teeth on the tool is nominally the same as that of the teeth onthe work gear and is of course zero in the case of a spur gear.

As shown most clearly in FIGS. 3-5, the flanks of the teeth 17 areserrated to provide flutes l8 and lands 19, the flutes extending atright angles to the axis of the tool. Alternate flutes start at the tipand at the root of the tooth flank and the flutes are distributedregularly, each flute in the tip series being midway between two flutesin the root series. The length of the flutes is preferably from 50 topercent of the length of the tooth flanks.

The flutes 18 on successive teeth 17 are staggered so that correspondingflutes on consecutive teeth form helices on the circumference of thetool at a helix angle The work cycle is as follows. The work gear isloaded into the machine at a position in which its axis is parallel tobut remote from that of the tool 14. After the tool has started torotate radial feed is applied to the work gear to bring them into mesh.Alternatively such radial feed could be applied to the tool. After theradial feed has terminated, at the required minimum distance between thecentres of the tool and the work gear, the tool is permitted to continuerotation for a predetermined time. Radial separation between the tooland the work gear then takes place. If desired, before radial separationis effected the tool may be run in the reverse direction for apredetermined length ,of time.

By adjusting the length and shape of the flutes in the tooth flanks ofthe tool to suit each particular application it is possible so tocontrol the flow of metal along the tooth flanks of the work gear as toachieve maximum accuracy of the finished product.

What I claim as my invention and desire to secure by Letters Patent is:

l. A toothed tool for finish forming, by rolling, a cylindrical orhelical work gear, said tool having, in the flanks of its teeth,serrations extending perpendicular to the axis of the tool which defineflutes in the tooth flanks and intervening lands, the flutes on eachtooth flank extending alternately from the tip towards the root and fromthe root towards the tip and extending along part only of the length ofthe tooth flank and being so disposed that corresponding flutes onsuccessive tooth flanks are disposed helically on the circumference ofthe tool.

2. A tool as claimed in claim 1, in which the length of the flutes isfrom 50 to 90 percent of the length of

1. A toothed tool for finish forming, by rolling, a cylindrical orhelical work gear, said tool having, in the flanks of its teeth,serrations extending perpendicular to the axis of the tool which defineflutes in the tooth flanks and intervening lands, the flutes on eachtooth flank extending alternately from the tip towards the root and fromthe root towards the tip and extending along part only of the length ofthe tooth flank and being so disposed that corresponding flutes onsuccessive tooth flanks are disposed helically on the circumference ofthe tool.
 2. A tool as claimed in claim 1, in which the length of theflutes is from 50 to 90 percent of the length of the tooth flanks.